A construction firm has admitted that a "cartel" of firms fixed bidding for contracts to do work on stadiums for the 2014 football World Cup, Brazilian authorities said Monday.

State antitrust authorities said the probe was linked to the notorious Petrobras corruption scandal that has snared numerous Brazilian politicians.

"There is evidence that at least five public calls for tender linked to work on World Cup stadiums were subject to a cartel," the Administrative Economic Defense Council (CADE), a state antitrust body, said in a statement.

It said construction firm Andrade Gutierrez had spilled the beans on the cartel activity after agreeing to cooperate with investigators in return for being spared sanctions.

Among the building or renovation projects involved were some on Rio de Janeiro's fabled Maracana Stadium and the Arena Pernambuco in Recife, it said.

Corruption probe

CADE said the probe was an offshoot of Operation Car Wash, an investigation by prosecutors into a $2 billion corruption affair at state oil firm Petrobras.